How do I install a posi unit??

[Dcm]

I have an open rearend. Looking to buy a posi unit. Eaton 4 series for my style truck. Hopefully someone has done this and can lend advice.

[davepl]

This is one that probably is too complicated to explain in text. I'd look for Youtube videos, or check the Extreme 4x4 or Trucks! sites (whatever they're now called). If the Eaton is anything like I think it is, you're going to need a dial indicator and some tooth contact paint, and you'll need to know how to shim it side to side to set the proper depth, and then there's a pinion sleeve that might or might not be a crush sleeve.

It's not that it can't be done, it's just one of the last things people wind up leaning to do themselves because its easier to learn it in person from someone than a book. After that it's automatic transmissions, AC, and upholstery. Then you'd know all there is to know.

[mechanicalman]

Originally Posted by Dcm

I have an open rearend. Looking to buy a posi unit. Eaton 4 series for my style truck. Hopefully someone has done this and can lend advice.

Are you staying with the same gear set you have now?

[Dcm]

Well I'm a long way from knowing all that

[mechanicalman]

Originally Posted by Dcm

Well I'm a long way from knowing all that

Have you selected a gear ratio, or a range of gear ratios to choose from? You must do this before buying a posi carrier. I have no idea what your skill level is on this, and if you need purchasing advice or installation advice.

[boraxman]

I would seriously have someone that does this do it.

[leddzepp]

Take it to a shop. If not set up properly your rear end will howl at the moon.

[Dcm]

Depending on the transmission I select, I'm going with either 3:73 or 4:10

[Dcm]

I fully intend on having someone with experience do the install. I just need to know if the Eaton 4 series is the correct on for my rearend. I also want to know if there are mods that have to be done in order to properly run a posi unit in my stock open rearend. Basically I don't wanna spend a lot of time and money modifying my rearend when I would have been money ahead to buy a new rearend already equipped with posi.

[boraxman]

Will fit your truck 12 bolt...Did this drill with my first c10 some years back.

I went with 3:42 on a 350/350 ~350hp and it was nice.

[54belair]

Personally, Id think about new gears also. If your rear has a lot of miles on it, the gears will have an established wear pattern. When you disasemble the rear , its difficult to set the gears back in as they were before---if you miss the set up you Could (could) end up with a howl in the rear.
I set up a 12 bolt many years ago, got lucky and it worked great---but on this build Im going to a local "rear end" guy.

[Bigdav160]

I've setup hundreds of rear axles. Way easier than most people know.

[mechanicalman]

Originally Posted by Bigdav160

I've setup hundreds of rear axles. Way easier than most people know.

X2! When I worked in the shops and dealerships, nobody wanted anything to do with differentials so I seemed to get more than my share of them. The first one I ever did, I botched and it died. (no case spreader, autopsy showed I cracked a bearing race). After that, they kept coming and I realized just how easy it was.

Never, ever used a pinion gauge and I've never, ever seen one except in pictues; my blood flows with gear marking compound.

That being said, I've never seen or used a case spreader either. I just think if I'd had one I'd be batting 1000.

[davepl]

Originally Posted by Bigdav160

I've setup hundreds of rear axles. Way easier than most people know.

Yeah. That's the point. Most people don't know. I've only done a few, and none howled, so it can't be that hard, as you say.

I find GM 12-bolts annoying. If you're just putting in a posi quite often the shim packs will stay the same, but you still need to know how to see the backlash/tooth engagement. And I'm one of the few that still think contact paint is a good idea, not sure how many still do that step.

[71matt]

I'm far from considering myself a mechanic, although i've learned and installed a few things with help from a brother who is a mechanic. That being said, there is a good "build" project on the "Trucks!" /Powerblock website for a c10, one episode covers a positrac rear end. Could be useful to you. good luck
Matt

[Dcm]

Thanks Matt. That's exactly what I needy

[WIDESIDE72]

How about this option:
http://www.carcraft.com/techarticles...ntal_upgrades/

[Dcm]

That actually sounds really good